Ritlecitinib is an investigational medication being tested in this clinical trial. In this study, participants will receive ritlecitinib in capsule form. The medication will be given in different ways to compare how the body absorbs it. Some participants will take the capsule whole, while others will open the capsule and sprinkle its contents on different foods such as applesauce, strawberry jam, or yogurt. The study will also look at whether eating food affects how well the body absorbs the medication when taken as a whole capsule.

Alopecia Areata – Alopecia Areata is a condition where the immune system mistakenly attacks hair follicles, causing hair loss. The hair loss typically occurs in round patches on the scalp, but it can affect any area of the body where hair grows. The condition can develop suddenly over just a few days or weeks. In some cases, the hair may grow back on its own, while in others, the hair loss may progress to larger areas. The severity varies from person to person, with some experiencing only small patches while others may lose all scalp hair or even all body hair. The condition can occur at any age and affects both men and women equally.

Rheumatoid Arthritis – Rheumatoid Arthritis is a chronic condition where the immune system attacks the lining of the joints, causing inflammation. The disease typically affects joints on both sides of the body, such as both wrists, hands, or knees. Symptoms include joint pain, swelling, stiffness, and warmth, which are often worse in the morning or after periods of rest. Over time, the inflammation can damage cartilage and bone within the joints, leading to joint deformity. The condition may also cause fatigue, low-grade fever, and loss of appetite. Rheumatoid Arthritis can also affect other organs and tissues in the body beyond the joints.

Vitiligo – Vitiligo is a condition where the skin loses its pigment cells, resulting in white patches on various parts of the body. The patches occur because cells called melanocytes, which produce skin color, are destroyed. The condition can affect any area of the skin, but it commonly appears on the face, hands, arms, and feet. The white patches may start small and gradually spread over time, though the rate and extent of color loss is unpredictable. Hair growing in affected areas may also turn white or gray. Vitiligo can begin at any age but often appears before the age of 30.

Ulcerative Colitis – Ulcerative Colitis is a chronic condition that causes inflammation and ulcers in the inner lining of the colon and rectum. The inflammation typically begins in the rectum and may spread continuously to involve other parts of the colon. Symptoms include diarrhea often with blood or pus, abdominal pain and cramping, rectal pain, and urgent need to have bowel movements. The condition usually develops gradually rather than suddenly. People with Ulcerative Colitis experience periods of flare-ups when symptoms worsen and periods of remission when symptoms improve or disappear. The severity ranges from mild to severe, affecting quality of life differently for each person.

Crohn’s Disease – Crohn’s Disease is a chronic condition that causes inflammation in any part of the digestive tract from the mouth to the anus. Unlike Ulcerative Colitis, the inflammation in Crohn’s Disease can occur in patches with healthy tissue in between and affects all layers of the bowel wall. Common symptoms include persistent diarrhea, abdominal pain and cramping, blood in the stool, reduced appetite, and weight loss. The inflammation can lead to complications such as narrowing of the bowel or abnormal connections between different parts of the intestine. Symptoms may develop gradually or appear suddenly. The condition typically involves periods of active disease alternating with periods of remission.